A pancreas cancer is one of the refractory cancers, and the 5-year survival rate of the whole pancreas cancer patient is estimated to be 2 to 3%. The number of the patients who died from the pancreas cancer has rapidly increased by approximately 2.5 times for the last 20 years, and the statistics showed that 26,791 people died from the pancreas cancer in 2009. The incidence and mortality of the pancreas cancer is almost same number, and the pancreas cancer occupies 6% of causes of the death from cancers in Japan and is fifth place next to lung, stomach, large intestine and liver in the mortality by the cancer of different parts.
A treatment for the pancreas cancer which is expected to be radical cure is only surgical resection, although approximately 10 to 20% of the whole pancreas cancer patients can actually undergo the radical resection, because many patients have been found with the condition of a progressive cancer (stage III+IV). A median survival period for each stage is approximately 12 to 30 months for Stage I and II, 9 to 11 months for Stage III and around 5 to 6 months for Stage IV, therefore the prognosis is very poor and it has been considered that there is a little possibility of the treatment for the patient, in particular who is unable to undergo the resection.
A gemcitabine has been used as a standard treatment for the progressive pancreas cancer, however other standard treatments have not been established, when the patient became refractory to the gemcitabine. The cases of good physical status are recognized in the patient with the progressive pancreas cancer when the patient became refractory to the gemcitabine, and it has been considered that a development of the effective treatment for such a patient group (pancreas cancer refractory to gemcitabine) is the important problem in the whole development of the therapeutics of pancreas cancer.
In recent years, it is reported that cells derived from pancreas cancer such as PANC-1, AsPC-1, BxPC-1 and KP-3 have strong tolerance to an extreme nutrient starvation state and that elimination of the tolerance may be a new biochemical approach in cancer therapy (Patent document 1).
It is reported that arctigenin was found to be effective as a material which can cancel the viability of tumor cells under undernutrition condition in the screening using pancreas cancer cell line PANC-1 (Non-patent document 1).
Here, in the Japanese Pharmacopoeia 15th edition, a burdock fruit is defined as a fruit of burdock, Arctium lappa Linne (Compositae). In addition, a burdock fruit is a herbal medicine prescribed for Gingyo-san, Kufugedoku-to, Shofusan and the like, and is classified into a primary material to be used as a pharmaceutical agent exclusively.
A burdock fruit contains approximately 7% of arctiin which is classified into lignan glycoside and approximately 0.6% of arctigenin which is an aglycone of arctiin. According to the above knowledge, it is expected that a burdock fruit extract containing arctigenin can be used as an anticancer agent for treating pancreas cancer.